This is a native BlackBerry 10 project. The user opens the app. There is a button to select a picture file. The user selects a picture file. The picture is scaled on the screen with a black background. On the bottom of the screen below the jpeg is a label showing file size and also a slider to change the jpeg compress quality 100-1(label shows what quality setting it is). As the user slides the slider the quality number changes. As the slider is released the file size is updated. This is all done in memory. There is a second slider beneath that that is 100%-1% that scales the picture size down and retains the aspect ratio. When the slider is slid the potential resulting file size is shown. There is a button that says "Done" that finalizes the compression and saves it to a file(the same directory it was grabbed from but with a different name. This must be done in Cascades native BlackBerry 10. Using open source c++: library I'll show you.